Stalk-eyed flies

Definition

A family of flies (Diptera: Diopsidae) distinguished by eyestalks—lateral projections of the head capsule bearing the compound eyes at their tips. The antennae arise from the stalk rather than the head midline, a unique condition among flies. Eyestalks are present in all Diopsinae but absent in Centrioncinae; when present, they are typically sexually dimorphic, with males bearing longer stalks than females.

Etymology

From English "stalk" (a slender supporting structure) + "eyed" (bearing eyes), referring to the lateral head projections that carry the compound eyes.

Example

Males of the African diopsid *Teleopsis dalmanni* compete for lekking sites and use their elongated eyestalks as weapons in male-male combat, with stalk length predicting fighting success.

Synonyms

• Diopsidae

Related Terms

• eyestalk
• Sexual dimorphism
• lekking
• compound eye
• Diptera
• antennal placement

Usage Notes

The term refers specifically to the family Diopsidae, not merely to any fly with projecting eyes; several unrelated families (Drosophilidae, Platystomatidae, Tephritidae) convergently evolved similar head shapes but retain midline antennae. "Stalk-eyed fly" is often used for individual species, while "stalk-eyed flies" denotes the family collectively. The eyestalk condition is diagnostic at family level only when combined with antennal position.